Are thousand years old egg good for the palate but bad for the health due to their potential heavy metal content?
The health concern, over this age-old Chinese delicacy, has been rekindled recently following reports of excessive lead found in the foodstuff in the mainland.
To address this concern, the Consumer Council has put to test a total of 19 samples of lime preserved eggs drawn from both retail outlets (sold in prepackage) and restaurants (sold as take-away).
The results, as borne out in these samples, are a great relief to the consumers of this traditional Chinese foodstuff savoured as a ready-to-eat appetizer or an ingredient in many a cooked dish.
Out of the 19 samples, 12 comprising 2 prepackaged and all of the 10 restaurant samples were detected free of both lead and arsenic.
However, these potentially toxic heavy metals did surface in the 7 remainders of the samples - either with arsenic only or with both.
Nonetheless, their levels were well below the maximum permitted concentration stipulated in the Food Adulteration (Metallic Contamination) Regulations of 6 mg/kg and 1.4 mg/kg for lead and arsenic respectively.
So, for normal consumption of lime preserved eggs, the concern for health risk seems unwarranted. But, of course, that does not mean that one can indulge on an eating binge of those eggs.
In the unlikely event that if a 60 kg adult happens to ingest in a week 800 grams or some 16 pieces of the lime preserved eggs detected with the highest lead content of 1.78 mg/kg in the test for a long period, one would have run the risk of exceeding the maximum tolerable level set in the PTWI (Provisional Tolerable Weekly Intakes) of WHO.
In the case of arsenic, a 60 kg adult would have to ingest 19 kilograms or some 380 pieces of the eggs detected with the highest total arsenic content of 0.47 mg/kg in the test for a long period, to exceed the PTWI limit of inorganic arsenic.
Lead is a chronic toxic chemical while inorganic arsenic is a known carcinogen to humans.
Besides heavy metal content, the test also investigated the sanitary level of such lime preserved eggs.
By means of an Aerobic Colony Count (ACC) which is a count of viable bacteria present in the food, all 9 prepackaged and 7 of the 10 restaurant samples were found to have an ACC of below 10,000 cfu/100 g.
Under the Food and Environmental Hygiene Department's (FEHD) microbiological guidelines, they were classified as Class A and deemed "satisfactory".
Three of the restaurant samples were detected to have a higher ACC level of between 10,000 and 100,000 cfu/100 g, but under the FEHD's guidelines, they were classified Class B and still considered "acceptable".
The foodstuff was generally free of E.coli and Salmonella contamination. The quantities of E.coli of all samples were below 10 cfu/100 g while Salmonella was undetected.
The test samples were also evaluated and compared for their quality - in terms of pH value and total alkalinity. For the discerning consumers, they would be delighted to learn that by and large the samples fared well in these tests.
All but one (a restaurant sample) met the requirement of pH value of the mainland standard (above 9.5) indicating that the preservation process of these eggs had been completed fully.
11 of 19 samples also met the requirement of the total alkalinity for premium eggs of the mainland standard (between 5 and 10 meq/100 g), which should give their consumers a "good mouth feel".
So, look up the report in this March issue of CHOICE and enjoy.
The Consumer Council reserves all its right (including copyright) in respect of CHOICE Magazine and Online CHOICE ( https://echoice.consumer.org.hk/ ).